12V Battery Charging Facts

[Maquis]

How close are the keys being stored to the car? Keep them at least 10m away.

Another data point: I’ve had my car for 42 months now. For the first 3 years, I left the fob on the cup holder. Car is in a locked garage. About 6 months ago, my wife started driving the MME so I set her up a profile on the other fob. I now set my fob on top of my toolbox in the garage about 3m away. I have never gotten any 12V messages - ever.

I really think it’s more about frequent movement of the key (be it phone or fob) in and out of Bluetooth range rather than its fixed location.

Sponsored

 

[FordMachEGo]

I think your math is off. If the 12V battery is charged 50% twice a day, that's one full charge per day. And you are saying that would be 1/4% of the HVB capacity (or 1/2% over 2 days). I think the HVB is much bigger than that! I have also left my car at the airport for about 5 days, and I saw no change in the HVB charge. So I agree with that.

When you leave your car for 6 weeks is it plugged in? I’m planning on leaving mine for 12 weeks and am wondering whether I should plug it in, disconnect the 12 v battery and/ or put it on a trickle charger. Anyone have any advice for this situation? What would be ideal? I could also have someone start up the car every once in a while.

 

[Barryb54]

All of this thread is extremely helpful to us all as well as prior posts & references to this topic by our knowledge-god, Mach-Lee. With that said, for those of us driving 2021 Job 1 models that have NEVER had any 12V warning or issues… should we replace our 12V battery after 36 months of use… or not? My car is there this month but only 25K miles & 98% charged at my house. Ty for any definitive guidance on this.

 

[Mach-e4x]

All of this thread is extremely helpful to us all as well as prior posts & references to this topic by our knowledge-god, Mach-Lee. With that said, for those of us driving 2021 Job 1 models that have NEVER had any 12V warning or issues… should we replace our 12V battery after 36 months of use… or not? My car is there this month but only 25K miles & 98% charged at my house. Ty for any definitive guidance on this.

Same here, 36 months, 24K miles, 99% L2 or L1 charged in my garage to 80%, no issues. I don't drive much so in the winter months the LVB can get too low to receive OTA updates. To help keep the LVB above 50% I will plug in the L1 110v EVSE from Ford overnight while it slowly charges the HVB to 80%.
As long as the LVB is healthy I'm going to keep it.

 

[Mach-Lee]

I really think it’s more about frequent movement of the key (be it phone or fob) in and out of Bluetooth range rather than its fixed location.

Correct, fob or PAAK movement is the major factor. This is difficult to explain, but walking around near your fobs when they are on the edge of detection range can also cause wakeups because your body affects the RF signal. Old timers will remember how walking around the room affected the TV signal, similar effect.

If nothing is moving near the fobs, then you are mostly fine, but in some rare cases the fobs being close were triggering the car due to glitchy software even with no movement.

The only minor issue I ever have with 12V drains is when I’m working in the garage and walking around with my phone. It keeps waking up the car so I have to quit FordPass. Besides that, never had an issue.

All of this thread is extremely helpful to us all as well as prior posts & references to this topic by our knowledge-god, Mach-Lee. With that said, for those of us driving 2021 Job 1 models that have NEVER had any 12V warning or issues… should we replace our 12V battery after 36 months of use… or not? My car is there this month but only 25K miles & 98% charged at my house. Ty for any definitive guidance on this.

12V lifetime depends heavily on climate and usage. Up here where I live, batteries last 5-7 years. In California they last about 3-4 years due to heat. I will probably be replacing mine at the 5 year mark if I keep the car that long. If I lived in LA, I’d probably replace it at 3 years.

 

[zvez]

Correct, fob or PAAK movement is a major factor. This is difficult to explain, but walking around near your fobs when they are on the edge of detection range can also cause wakeups because your body affects the RF signal. Old timers will remember how walking around the room affected the TV signal.

If nothing is moving near the fobs, then you are mostly fine, but in some rare cases the fobs being close were triggering the car due to glitchy software even with no movement.



12V lifetime depends heavily on climate and usage. Up here where I live, batteries last 5-7 years. In California the last about 3-4 years due to heat. I will probably be replacing mine at the 5 year mark if I keep the car that long. If I lived in LA, I’d probably replace it at 3 years.

that explains how I can walk out in the garage and car wakes up, because I walk by the table where the fob is. It's about 20 feet from the car.

 

[James III]

How close are the keys being stored to the car? Keep them at least 10m away. Here are all the drain causes: https://www.macheforum.com/site/thr...-system-drain-service-required-message.36140/

I would put the BCM configuration back to factory and do additional testing. It is possible that could cause an issue since the feature isn't supported in the UK.

Hi again,
I know the key is not an issue because the UK key falls Rail asleep within minutes if un moved and is completely inactive. It’s not even recognised in the car if it’s sitting there in the car is turned off. It won’t start again until the key is picked up. But in this case the office key cab is more than 10m from workshop.

I will suggest tech to put the BCM configuration back to factory default.

Will that require FORSCAN to disabled WAL?

Today they sent a video to Ford chilling the BCM clicking on and off at regular intervals.

Thanks again for your support!

 

[Shayne]

All of this thread is extremely helpful to us all as well as prior posts & references to this topic by our knowledge-god, Mach-Lee. With that said, for those of us driving 2021 Job 1 models that have NEVER had any 12V warning or issues… should we replace our 12V battery after 36 months of use… or not? My car is there this month but only 25K miles & 98% charged at my house. Ty for any definitive guidance on this.

Depends on the environment and abuse. Up here where it is not too hot 12V batteries in my ICE vehicles last/lasted a decade or more. Down in Arizona maybe a different story. Abuse and lack of a proper BMS also may lead to shorter life span. Not sure with this vehicle as I have not had enough time with it to date. I am on my second 12V in 3.5 years but a faulty HVBJB killed the first (abuse).

 

[Maquis]

Correct, fob or PAAK movement is the major factor. This is difficult to explain, but walking around near your fobs when they are on the edge of detection range can also cause wakeups because your body affects the RF signal. Old timers will remember how walking around the room affected the TV signal, similar effect.

If nothing is moving near the fobs, then you are mostly fine, but in some rare cases the fobs being close were triggering the car due to glitchy software even with no movement.

The only minor issue I ever have with 12V drains is when I’m working in the garage and walking around with my phone. It keeps waking up the car so I have to quit FordPass. Besides that, never had an issue.



12V lifetime depends heavily on climate and usage. Up here where I live, batteries last 5-7 years. In California the last about 3-4 years due to heat. I will probably be replacing mine at the 5 year mark if I keep the car that long. If I lived in LA, I’d probably replace it at 3 years.

Makes sense. Mine is probably close enough that walking past it doesn’t interrupt the signal.

 

[Barryb54]

Correct, fob or PAAK movement is the major factor. This is difficult to explain, but walking around near your fobs when they are on the edge of detection range can also cause wakeups because your body affects the RF signal. Old timers will remember how walking around the room affected the TV signal, similar effect.

If nothing is moving near the fobs, then you are mostly fine, but in some rare cases the fobs being close were triggering the car due to glitchy software even with no movement.

The only minor issue I ever have with 12V drains is when I’m working in the garage and walking around with my phone. It keeps waking up the car so I have to quit FordPass. Besides that, never had an issue.



12V lifetime depends heavily on climate and usage. Up here where I live, batteries last 5-7 years. In California they last about 3-4 years due to heat. I will probably be replacing mine at the 5 year mark if I keep the car that long. If I lived in LA, I’d probably replace it at 3 years.

Perfect. Exactly what I was looking for. Ty! Just decided to exercise my option to buy the car. Will hang on to it for another few years. Still the best looking EV on the market… if you ask me! ?

 

[guinn]

Maybe….I ballparked it in my head. Let’s do it for real.

The 12V battery is 35AH. 35 x 12 = 420WH. If it discharged 45% in 10 hours, that’s roughly 0.45 kwh in a day or 0.9kWh in 2 days. 0.9 kWh / 91 kWh = 1%. So I was off, it‘s actually worse!

It‘s getting late - I’d be happy if someone else looked at - maybe I missed something.

I believe your calculations are correct. I have no idea why my 12V battery was dropping so quickly.

Here are some readings I took. The battery SOC is approximate in each case based on the chart.

5/27/2023​	7:30 AM​	12.91​	100%
	8:30 AM​	12.83​	95%
	9:00 AM​	12.78​	90%
	10:30 AM​	12.71​	85%
	11:30 AM​	12.67​	80%
	12:30 PM​	12.62​	75%
	1:30 PM​	12.58​	75%
	2:30 PM​	12.54​	70%
	4:00 PM​	12.49​	70%
	5:00 PM​	12.46​	65%
	6:00 PM​	12.43​	60%
	7:30 PM​	12.39​	60%
	8:30 PM​	12.37​	55%

 

[rreddy3]

FWIW, re: fobs waking car up, and human walking near fob waking it up that wakes car up, you might consider faraday fob pouches as a way to avoid those drains on the LVB.

I bought some “Mission Darkness” fob size farady pouches. A two pack is about 15 USD. They seem well made and they work as intended.

I can tell you from first hand experience/testing if you have the fob in the pouch and walk up to the car, it has no clue you’re there.

No lights, no clickityclack sounds, nothing. The car just sleeps away. By the same token I would guess if fob is in its pouch, walking by it won’t wake things up and create a voltage drain. I don’t use paak, so that is not a LVB voltage drain issue for me.

 

[KDub]

I have a 2021 Job 1. I haven't received an OTA since the Tesla Supercharger update many months ago. Every time I check my 12V it's never higher that 67%, even after drives of 45 minutes or a L2 charge to 90%. Is this normal? Is my low 12V charge why my OTAs have stalled?

 

[zvez]

I believe your calculations are correct. I have no idea why my 12V battery was dropping so quickly.

Here are some readings I took. The battery SOC is approximate in each case based on the chart.

5/27/2023​	7:30 AM​	12.91​	100%
	8:30 AM​	12.83​	95%
	9:00 AM​	12.78​	90%
	10:30 AM​	12.71​	85%
	11:30 AM​	12.67​	80%
	12:30 PM​	12.62​	75%
	1:30 PM​	12.58​	75%
	2:30 PM​	12.54​	70%
	4:00 PM​	12.49​	70%
	5:00 PM​	12.46​	65%
	6:00 PM​	12.43​	60%
	7:30 PM​	12.39​	60%
	8:30 PM​	12.37​	55%

this is a stunning drop, surely you must have a drain somewhere?

 

[zvez]

I have a 2021 Job 1. I haven't received an OTA since the Tesla Supercharger update many months ago. Every time I check my 12V it's never higher that 67%, even after drives of 45 minutes or a L2 charge to 90%. Is this normal? Is my low 12V charge why my OTAs have stalled?

I think since 21 they've changed 12v battery management. On my 23.5 out of curiosity I check the 12v SOC. in eleven months it's never read less than 80% on the ford.com site and usually resides in the 85-95% range. The BEV team when I was discussing an issue with charging as an aside told me that some OTAs require 80% battery state of charge to work.

Sponsored